Digital signal processing method, data recording and reproducing apparatus, and data recording medium that are resistant to burst errors

ABSTRACT

With two consecutive product-coded ECC blocks, EB 1  and EB 2,  as a set, the rth row of first ECB block EB 1  is followed by the rth row of second ECC block EB 2  in such a way that the first row of first ECC block EB 1  is followed by the first row of second ECB block EB 2,  which is followed by the second row of first ECC block ECB 1,  which is followed by the second row of second ECC block EB 2,  and so on, to interleave data on a row basis. That is, data of two ECC blocks, EB 1  and EB 2,  is allocated alternately on a row basis. This allocation method allows an error to be distributed after reproduction even when a serious burst error extending 18 rows occurs in an ECC block.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a digital signal processingmethod, a data recording and reproducing apparatus, and a data recordingmedium, and more particularly to a digital signal processing method, adata recording and reproducing apparatus, and a data recording mediumthat are suitable for signal processing on a high-density recordingmedium.

[0003] 2. Description of the Related Art

[0004] Recently, data recording media have become denser. For example,as compared with a CD (Compact Disk), a DVD (Digital Versatile Disk) hasa shorter minimum mark length and a higher track density with the trackpitch of 0.74 μm that is shorter than half of that of a CD. The userrecording capacity of a single-sided, single-layer DVD is 4.7 GB.

[0005] As a replacement of a disk in the current generation in whichared laser beam is used, manufacturers are now studying anext-generation super high-density optical disk that uses a violet laserbeam (GaN). The user recording capacity of the next-generation opticaldisk is said to exceed 20 GB. Naturally, it will have a shorter minimummark length and a shorter track pitch, each about half of that of theDVD. On such a high-density disk, a defect developed during diskmanufacturing or dust or a scratch during use, if any, would be twice aslarge as that on the DVD in view of the relative data length.

[0006] For example, on a DVD, product coding (product coding is a codingof an error correction such as a product error correction coding) isperformed for a set of 192×172 DVD data bytes to generate 10 columns ofPI parity data for the rows and 16 rows of PO parity data for thecolumns, as shown in (A) in FIG. 1. As a result, a 208×182 bytes of ECC(Error Correction Code) block is built. Also, as shown in (B) in FIG. 1,one row of PO parity data is inserted every 12 rows to interleave datawith PO parity data.

[0007] As shown schematically in FIG. 2, the first row to the 208th rowof the first ECC block EB1 are written sequentially on a DVD, followedsequentially by the first row to the 208th row of the second ECC blockEB2, and so on.

[0008] In this method, up to 16 rows may be erasure-corrected with POparity data. This means that a disk error caused by a continuous diskdefect of up to 6 mm in length may be corrected. A continuous error likethis is called generally as a burst error. When the linear density isdoubled in this format, the maximum length of a correctable defect willbe reduced to 3 mm. On the other hand, five symbols (bytes) may beusually corrected with PI parity data and, if there is no random error,the maximum length of a correctable burst error on a DVD is about 10 μm.Therefore, when the linear density is doubled, the maximum length of adefect correctable with PI parity data will be reduced to 5 μm.

[0009] Therefore, if there is a random error, the length of a bursterror correctable with PI and PO parity data becomes much shorter in theconventional digital signal processing method and on the data recordingmedium described above. It should be noted that DVD PO rows areinterleaved with data rows, not to distribute burst errors, but to keepthe parity data ratio constant and therefore there is no effect ofincreasing the correction length.

[0010] To solve this problem, the number of parity data units may beincreased to make the correction length longer. However, this method isdisadvantageous to high-density recording because parity data redundancyin the ECC block increases.

SUMMARY OF THE INVENTION

[0011] In view of the foregoing, it is an object of the presentinvention to provide a digital signal processing method, a datarecording and reproducing apparatus, and a data recording medium capableof increasing the maximum burst-error correctable length relativelyeasily without increasing redundancy.

[0012] It is another object of the present invention to provide adigital signal processing method, a data recording and reproducingapparatus, and a data recording medium capable of distributingrelatively short burst errors and thereby increasing the data lineardensity.

[0013] To solve the above problems, there is provided a digital signalprocessing method for recording and reproducing digital signals of datato and from a recording medium on an ECC (Error Correction Code) blockbasis, the ECC block being generated by product-coding a predeterminednumber of words of digital signals and parity data, wherein, with n(n≧2) consecutive ECC blocks as a set, kth rows of the ECC blocks arerecorded sequentially and then (k+1)th rows are recorded sequentiallyfor all rows of the ECC blocks in such a way that first rows of the ECCblocks of the set are recorded sequentially and then second rows arerecorded sequentially on the recording medium.

[0014] When a serious burst error extending two or more ECC blocksoccurs, the method according to the present invention distributes data,reproduced from a recording medium containing the burst error, after thedata is de-interleaved.

[0015] To solve the above problems, there is provided a digital signalprocessing method for recording and reproducing digital signals of datato and from a recording medium on an ECC block basis, the ECC blockbeing generated by product-coding a predetermined number of words ofdigital signals and parity data, wherein, with two consecutive ECCblocks as a set, a sequence of operations is repeated for all rows ofthe two ECC blocks of the set, the sequence of operations being executedin such a way that an odd-numbered data unit in a first row of one ofthe ECC blocks of the set and an even-numbered data unit in a first rowof the other ECC block are alternately switched on a data unit basis andrecorded on the recording medium and then an even-numbered data unit inthe first row of one of the ECC block and an odd-numbered data unit inthe first row of the other ECC block are alternately switched on a dataunit basis and recorded on the recording medium.

[0016] When an error smaller in size than one ECC block occurs atreproduction time, the method according to the present inventiondistributes data, reproduced from a recording medium containing theburst error, after the data is de-interleaved.

[0017] To solve the above problems, there is provided a data recordingand reproducing apparatus that records and reproduces digital signals ofdata to and from a recording medium on an ECC block basis, the ECC blockbeing generated by product-coding a predetermined number of words ofdigital signals and parity data, the apparatus comprising: ECC blockgenerating means for generating ECC blocks by a product-coding method,each ECC block including a predetermined number of words of main data,auxiliary information including a sector address, and parity data;interleaving means for sequentially outputting, with n (n≧2)consecutiveECC blocks as a set, kth rows and then (k+1)th rows of the ECC blocks ofthe set in such a way that first rows of the ECC blocks of the set areoutput sequentially and then second rows are output sequentially, theconsecutive ECC blocks being included in the ECC blocks generated by theECC block generating means; recording means for recording signals,output by the interleaving means, on the recording means with frame synccodes attached; reproducing means for reproducing the signals from therecording medium; de-interleaving means for de-interleaving the signalsreproduced by the reproducing means based on the sector addresses andfor outputting the ECC blocks arranged in an original order; anddecoding means for de-modulating the main data using data in the ECCblocks obtained by the de-interleaving means.

[0018] In a preferred embodiment of the present invention, the ECC blockgenerating means sequentially generates a plurality of ECC blocks eachcomposed of a predetermined number of words and each comprising aplurality of divided data sectors each being one of two M×(N/2) datasectors generated by dividing an M×N data sector composed of the maindata and the auxiliary information, into two in a column direction; apredetermined number of bytes of first parity data generated fromrow-direction elements of the plurality of divided data sectors; and apredetermined number of bytes of second parity data generated fromcolumn-direction elements of the divided data sectors, the first paritydata or the second parity data being generated from the row-directionelements of the second parity data or the column-direction elements ofthe first parity data, with two consecutive ECC blocks, generated by theECC block generating means, as a set, the interleaving meanssequentially outputs kth rows, and then sequentially outputs (k+1)throws, of two divided data sectors corresponding to each of the ECCblocks in such a way that each of first rows of the two divided datasectors, each belonging to one of the ECC blocks of the set, andcorresponding first parity data are output sequentially and then each ofsecond rows is output sequentially and, each time M rows of the twodivided data sectors are output, the second parity data is outputalternately for one and the other of the two ECC blocks alternately, andthe recording means records the signals, output by the interleavingmeans, with the frame sync codes attached at a regular interval.

[0019] In a preferred embodiment of the present invention, the ECC blockgenerating means sequentially generates a plurality of ECC blocks eachcomposed of a predetermined number of words and each comprising aplurality of divided data sectors each being one of two M×(N/2) datasectors generated by dividing an M×N data sector composed of the maindata and the auxiliary information, into two in a column direction; apredetermined number of bytes of first parity data generated fromrow-direction elements of the plurality of divided data sectors; and apredetermined number of bytes of second parity data generated fromcolumn-direction elements of the divided data sectors, the first paritydata or the second parity data being generated from row-directionelements of the second parity data or column-direction elements of thefirst parity data, and with two consecutive ECC blocks, generated by theECC block generating means, as a set, the interleaving meanssequentially outputs kth rows, and then sequentially outputs (k+1)throws, of two divided data sectors corresponding to each of the ECCblocks in such a way that each of first rows of the two divided datasectors, each belonging to one of the ECC blocks of the set, andcorresponding first parity data are output sequentially and then each ofsecond rows is output sequentially and, each time (2×M) rows of the twodivided data sectors are output, the second parity data is output forthe two ECC blocks.

[0020] To solve the above problems, there is provided a data recordingand reproducing apparatus that records and reproduces digital signals ofdata to and from a recording medium on an ECC block basis, the ECC blockbeing generated by product-coding a predetermined number of words ofdigital signals and parity data, the apparatus comprising: ECC blockgenerating means for generating ECC blocks by a product-coding method,each ECC block including a predetermined number of words of main data,auxiliary information including a sector address, and parity data;interleaving means for repeating, with two consecutive ECC blocks as aset, a sequence of operations for all rows of the two ECC blocks of theset, the sequence of operations being executed in such a way that anodd-numbered data unit in a first row of one of the ECC blocks of theset and an even-numbered data unit in a first row of the other ECC blockare alternately switched on a data unit basis and then an even-numbereddata unit in the first row of one of the ECC block and an odd-numbereddata unit in the first row of the other ECC block are alternatelyswitched on a data unit basis; recording means for recording signals,output by the interleaving means, on the recording means with frame synccodes attached; reproducing means for reproducing the signals from therecording medium; de-interleaving means for de-interleaving the signalsreproduced by the reproducing means based on the sector addresses andfor outputting the ECC blocks arranged in an original order; anddecoding means for de-modulating the main data using data in the ECCblocks obtained by the de-interleaving means.

[0021] To solve the above problems, there is provided a data recordingmedium on which digital signals of data are recorded on an ECC blockbasis, the ECC block being generated by product-coding a predeterminednumber of words of digital signals and parity data, wherein, with n(n≧2)consecutive ECC blocks as a set, kth rows of the ECC blocks arerecorded sequentially and then (k+1)th rows are recorded sequentiallyfor all rows of the ECC blocks in such a way that first rows of the ECCblocks of the set are recorded sequentially and then second rows arerecorded sequentially.

[0022] Even when a burst error extending two or more ECC blocks occursat reproduction time, the recording medium according to the presentinvention distributes the position of data, which includes erroneousreproduction signals, between two or more ECC blocks after the signalsare de-interleaved.

[0023] To solve the above problems, there is provided a recording mediumon which digital signal of data are recorded on an ECC block basis, theECC block being generated by product-coding a predetermined number ofwords of digital signals and parity data, wherein, with two consecutiveECC blocks as a set, a sequence of operations is repeated for all rowsof the two ECC blocks of the set, the sequence of operations beingexecuted in such a way that an odd-numbered data unit in a first row ofone of the ECC blocks of the set and an even-numbered data unit in afirst row of the other ECC block are alternately switched on a data unitbasis and then an even-numbered data unit in the first row of one of theECC block and an odd-numbered data unit in the first row of the otherECC block are alternately switched on a data unit basis.

[0024] Even when an error occurs in an ECC block at reproduction time,the error occurrence positions of the reproduced signals afterde-interleaving may be at least a predetermined distance apart.

[0025] The nature, principle and utility of the invention will becomemore apparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the accompanying drawings:

[0027]FIG. 1 is a diagram showing the configuration of an ECC block in aconventional method;

[0028]FIG. 2 is a diagram showing an example of data allocation on aconventional data recording medium;

[0029]FIG. 3 is a diagram showing data allocation on a data recordingmedium in a first embodiment of the present invention;

[0030]FIG. 4A is a diagram showing the distribution of an error in theECC blocks after de-interleaving at reproduction time in theconventional method;

[0031]FIG. 4B is a diagram showing the distribution of an error in theECC blocks after de-interleaving at reproduction time in the firstembodiment of the present invention;

[0032]FIG. 5 is a block diagram of an embodiment of a data recording andreproducing apparatus according to the present invention;

[0033]FIG. 6 is a diagram showing an example of a memory map of twomemories, one before interleaving and the other after interleaving, ofthe recording system in FIG. 5;

[0034]FIG. 7 is a diagram showing the configuration of a data sector ona DVD;

[0035]FIG. 8 is a diagram showing an example of the configuration ofphysical sectors in FIG. 5;

[0036]FIG. 9 is a diagram showing another example of a memory map of twomemories, one before interleaving and the other after interleaving, ofthe recording system in FIG. 5;

[0037]FIG. 10 is a diagram showing another representation of the memorymap of two memories in FIG. 9;

[0038]FIG. 11 is a diagram showing still another example of a memory mapof two memories, one before interleaving and the other afterinterleaving, of the recording system in FIG. 5;

[0039]FIG. 12 is a diagram showing an example of the configuration ofphysical sectors in FIGS. 9 and 10;

[0040]FIG. 13 is a diagram showing data allocation on a data recordingmedium in a second embodiment of the present invention; and

[0041]FIG. 14 is a diagram showing the distribution of errors in the ECCblocks after de-interleaving at reproduction time in the data shown inFIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Next, some embodiments according to the present invention will bedescribed below with reference to the drawings.

[0043] <First Embodiment>

[0044]FIG. 3 shows the layout of data on a data recording medium in afirst embodiment according to the present invention. In this embodiment,an interleave method is used in which data, which iserror-correction-coded by the product coding method, is distributed on arecording medium. As shown in FIG. 3, with two consecutive product-codedECC blocks, EB1 and EB2, as a set, the first row of the first ECC blockEB1 is followed by the first row of the second ECC block EB2, which isfollowed by the second row of the first ECC block EB1, which is followedby the second row of the second ECC block EB2, and so on. That is, therth row of the first ECC block is followed by the rth row of the secondECC block EB2. In this way, data is interleaved on a row basis.

[0045] That is, in this embodiment, data in two ECC blocks, EB1 and EB2,are alternated on a row basis. The two ECC blocks, EB1 and EB2, are eachconfigured as a product code block shown in FIG. 1. In addition, like aDVD, one PO parity row is inserted every 12 rows of data to keep theratio of parity data in one sector constant.

[0046] Assume that a serious burst error has occurred, for example, inconsecutive 18 rows in the ECC blocks in this embodiment as shown inFIG. 3. At reproduction time, the error is distributed between two ECCblocks after de-interleaving as shown in FIG. 4B. That is, the error isin nine rows in the first ECC block EB1 and in nine rows in the secondECC block EB2.

[0047] On the other hand, assume that the same burst error describedabove has occurred in consecutive 18 rows in the first ECC block asshown in FIG. 2 on the conventional recording medium shown in FIG. 2. Atreproduction time, the error is in the ECC block after de-interleavingas shown in FIG. 4A. That is, the error is in consecutive 18 rows of theECC block EB1.

[0048] Although there is a slight difference in the error distributionratio depending upon the burst error start and end positions in the rowswhere the burst error has occurred, the error processed by the method inthis embodiment shown in FIG. 4B is distributed more widely than theerror processed by the conventional method shown in FIG. 4A, asindicated by comparison between FIG. 4A and FIG. 4B. The result is thatthe effect of errors is diminished to ½. That is, although the error isnot distributed in each row and the correction length is not increasedin this embodiment, the number of rows affected by the error in eachcolumn is reduced to ½ of that in the conventional method.

[0049] In this case, an erasure-correction with PO parity data cannot bemade in the conventional method shown in FIG. 4A, because the maximumnumber of correction rows of 16 is exceeded. On the other hand, thenumber of error rows in each ECC block in this embodiment is nine asshown in FIG. 4B. Because the maximum number of correction rows of 16 isnot exceeded, the error may be corrected. The burst error correctionlimit in the conventional method is about 3 mm that corresponds to 16rows if the recording linear density of a DVD is doubled, whereas theburst error correction limit in the method according to the presentinvention is about 6 mm as on a DVD. If the recording linear density isthe same as that of a DVD, about 12 mm of a burst error may becorrected. That is, the correction length may be doubled withoutincreasing redundancy.

[0050] With n (n≧2) consecutive produce code blocks (ECC blocks) as aset, the rth rows of the first to nth ECC blocks may also besequentially arranged. In this case, a serious burst error isdistributed among n ECC blocks. The effect of an error in one ECC blockis reduced to 1/n as compared with that in the conventional method, andthe burst correction length may be increased to n times.

[0051] Next, a data recording and reproducing apparatus according to thepresent invention will be described. FIG. 5 is a block diagram showingan embodiment of the data recording and reproducing apparatus of thepresent invention. In this embodiment, the present invention is appliedto a DVD recording and reproducing apparatus. First, the configurationand the operation of the recording system will be described. An MPEGencoder 11 compresses and encodes video data and audio data using theMPEG standard, which is known, and sends the encoded data to a staticrandom access memory (SRAM) 12 as main data.

[0052] At the same time, a four-byte ID, composed of a low-orderthree-byte sector address and high-order one-byte disk information data,is sent to an IED encoder 13. This encoder adds a two-byte ID errorcorrection parity IED to the ID and then sends it to the SRAM 12. TheIED is generated using RS (6, 4, 3). RS (a, b, c) is a Reed Solomon codewhere a is the code word length, b is the number of data units, and c isthe minimum code-to-code distance.

[0053] The SRAM 12 receives the main data, ID and IED, and six-byte copyprotect information CP, temporarily stores them, reads a total of 2060bytes composed of 2048-byte main data, ID, IED, and CP, and sends themto an EDC encoder 14. This encoder generates an error detection paritycode (EDC: error detection code). A CRC (Cyclic Redundancy Code) is usedto generate an EDC. The generated EDC is written in the SRAM 12.

[0054] The 2064-byte data, composed of the EDC generated by the EDCencoder 14 and the 2060-byte data described above, is sent to a maindata scrambler 15. This scrambler uses sector addresses to scramble onlythe 2048-byte main data. The detail of the scramble method is notdescribed here because it is not related directly to the presentinvention. The scrambled data, that is, 2048-byte scrambled main data,is written in the SRAM 12. In the memory map of the SRAM 12, theaddresses are allocated as indicated by the map in (A) in FIG. 6. Atthis time, an area is reserved for later use in ECC parity datageneration.

[0055] The 2064-byte data described above, called a data sector on aDVD, is composed of 172 columns (bytes)×12 rows as shown in FIG. 7. Thelow-order three bytes of the first four-byte ID contain a sectoraddress, which is incremented by one for each consecutive data sector.In FIG. 7, “CPR_MAI” indicates the copy protect information CP describedabove. “M0”, “M1”, and “M2047” indicate the first byte, second byte, and2048th byte of the main data, respectively.

[0056] In the SRAM 12, the 2064-byte data described above is allocatedalternately, on a data sector basis, as shown in (A) in FIG. 6. Thisconfiguration sequentially arranges the sector numbers on the memory mapin a DRAM 19, that is, the sector numbers written on the disk. Even if apart of sector addresses cannot be read due to a defect at reproductiontime that will be described later, this configuration assures sectoraddress continuity and therefore makes it possible to predict an addressthat cannot be read. To allow the start of an ECC block, which will begenerated later, to be identified at reproduction time, the low-orderfive bits of the sector address in data sector 1 of ECC block 1 in (A)in FIG. 6 must always be set to “00000B”.

[0057] When 32 data sectors are accumulated in the SRAM 12 in this way,a total of 16 odd-numbered data sectors, that is, 172 columns(bytes)×192 rows, are accessed in the column direction in the SRAM mapshown in (A) in FIG. 6 and are passed to an ECC-PO encoder 16. Using RS(208, 192, 17), this encoder generates 16 bytes of PO parity data (outerparity) and writes it in the PO parity area in the SRAM 12. Thisprocessing is performed for the 172 columns to accumulate the generatedparity data in the PO parity area indicated by I in the memory map ofSRAM 12 shown in (A) in FIG. 6.

[0058] Next, 172 bytes of data are accessed in the row direction of theSRAM map in (A) in FIG. 6 and are passed to an ECC-PI encoder 17. UsingRS (182, 172, 11), this encoder generates 10 bytes of PI parity data(inner parity) and writes it in the PI parity area in the SRAM 12. Thisprocessing is performed for the 208 rows (=192 rows+16 rows) toaccumulate the generated parity data in the PI parity area indicated byII in the memory map of SRAM 12 shown in (A) in FIG. 6. This 182×208block forms ECC block 1.

[0059] Similarly, for the even-numbered 16 data sectors out of 32sectors accumulated in the SRAM 12, that is, 172 columns×192 rows data,PO parity data and PI parity data, which are product code, are generatedand written in the SRAM 12. In the memory map of the SRAM 12, 182×208ECC block 2 is accumulated as shown in (A) in FIG. 6. It should be notedthat, when the product code described above is used, 192 rows of PIparity data may be generated first and then 182 columns of PO paritydata may be generated.

[0060] Next, an interleave processor 18 accesses data in the SRAM 12 inthe order in which data is actually recorded on an optical disk 23, thatis, reads data while interleaving, and writes it in the DRAM 19. Thatis, from the SRAM 12, the interleave processor 18 reads 182 bytes fromthe first row of the first ECC block 1, then 182 bytes from the firstrow of the second ECC block 2, then 182 bytes from the second row of thefirst ECC block 1, then 182 bytes from the second row in the second ECCblock 2, and so on, alternately between two ECC blocks.

[0061] The PO parity rows of the two ECC blocks are read for each sectorof each ECC block. For example, after the last row (that is, 12th row)of the first sector of the second ECC block 2 is read, the first POparity row of the first ECC block 1 is read and then the first PO parityrow of the second ECC block 2 is read. In this way, after each twosectors are read, the PO parity rows are read sequentially from the twoECC blocks, one row from each ECC block.

[0062] The data and parity data read by the interleave processor 18 fromthe SRAM 12 are written in the dynamic random access memory (DRAM) 19.Therefore, the memory map of the DRAM 19 is as shown in (B) in FIG. 6.In this way, data is accumulated in the DRAM 19 in the same order inwhich data is allocated on the disk shown in FIG. 3.

[0063] Note that the DRAM 19 is provided to adjust the differencebetween the rate at which data is transferred from the MPEG encoder 11and the rate at which data is transferred to the optical disk 23 forwriting. In this case, the rate at which data is transferred to theoptical disk 23 is set higher than the rate at which data is transferredfrom the MPEG encoder 11. This transfer rate setting makes data-readtransfer from the DRAM 19 higher than data-write transfer to the DRAM19. Therefore, the DRAM 19 never becomes full, and data sent from theMPEG encoder 11 is never discarded.

[0064] When the DRAM 19 becomes empty, the drive stops writing to theoptical disk 23 (reading from the DRAM 19) and waits for data to beaccumulated in the DRAM 19. In general, the drive enters the still state(one track back jump per rotation of the spindle motor, not shown, thatrotates the optical disk 23). When data is accumulated in the DRAM 19 tosome degree, the drive resumes writing data on the optical disk 23 fromthe point at which writing to the optical disk 23 stopped.

[0065] A modulation and frame sync adding unit 20 reads data and paritydata sequentially from the DRAM 19, shown in (B) in FIG. 6, from left toright and from top to bottom and modulates the data (8/16 modulation inthe case of DVD). The unit also adds a frame sync code, which will beused for synchronizing data at reproduction time, every 91 bytes andsends the data to an NRZI converter 21.

[0066] The NRZI converter 21 NRZI-converts (the state is inverted by alogical value “1”) the input signal, sends the converted signal to apickup 22, modulates the intensity of a laser beam emitted from thelaser beam source within the pickup 22, focuses the modulated laser beamon the optical disk 23 (writable DVD), which is rotated by a spindlemotor not shown, and records the data on the disk. Therefore, the rowsare recorded on the optical disk 23 alternately from two ECC blocks, EB1and EB2, as shown in FIG. 3. After ECC block EB2, the rows from EB3 andEB4 are alternately written. Thereafter, the rows from two consecutiveECC blocks are recorded similarly.

[0067] Although data is interleaved when read from the SRAM 12 in theabove description, data may also be interleaved when written into theDRAM 19. In addition, data may be interleaved when written into the SRAM12, and the EDCs and ECCs may be generated by reading the data whilede-interleaving it.

[0068] In addition, though two memories (SRAM 12 and DRAM 19) are used,only the DRAM may be used. In this case, data is interleaved whenwriting data to, or reading data from, the DRAM. For example, data iswritten as shown in the DRAM map in (B) in FIG. 6, and such operationsas EDC generation, data scrambling, and ECC generation are performedwhile accessing the DRAM. Then, data is read sequentially beginning fromthe first row and then written on the optical disk 23.

[0069] Next, the configuration and the operation of the reproductionsystem will be described. The pickup 22 focuses apredetermined-intensity laser beam onto the optical disk 23 rotated bythe spindle motor not shown. A light reflected on the signal recordingsurface of the optical disk 23 is sent to the pickup 22 and isphoto-electrically converted. The obtained read signal is sent to asignal processor 24, which performs signal processing (PF amplification,shaping, bit PLL) for the signal. The bit clock extracted through bitPLL is sent to an NRZ conversion and sync detector 25, whichNRZ-converts the signal based on the bit clock and detects the framesync code to find the data byte delimiter (that is, establishes framesynchronization).

[0070] As will be described later, when establishing framesynchronization, the NRZ conversion and sync detector 25 establishesframe synchronization first and then sector synchronization. Thereproduced signal, for which frame synchronization and sectorsynchronization have been established in this manner, is sent to ademodulator 26 (8/16 demodulation) for demodulation and then sent to anID detector 27 and a de-interleave processor 28. Note that the ID in thesignal output from the demodulator 26 includes a three-bit sectoraddress. This sector address is incremented by one for each of 16sectors of an ECC block and is initialized for each ECC block.

[0071] The ID detector 27 detects the ID in the reproduced signal andsends the sector address included in the ID to a servo controller 36 foruse in the drive seek operation. If the reproduced signal is sent froman address on the optical disk 23 not desired by the user, the servocontroller 36 performs seek operation in which the pickup 22 is moved toa desired sector address on the optical disk 23. On the other hand, ifthe address is a desired sector address, the de-interleave processor 28writes the reproduced signal in an SRAM 29 while de-interleaving data.

[0072] Based on the sector address sent from the ID detector 27, thede-interleave processor 28 detects the start (ECC block sync code) ofthe ECC block in the demodulated signal sent from the demodulator 26 anddetermines which of the two consecutive ECC blocks the received ECCblock is. Then, the de-interleave processor 28 writes data into the SRAM29 while addressing (de-interleaving) data such that the data isallocated in the same manner as in the memory map in (A) in FIG. 6.

[0073] Note that the de-interleave processor writes data into the SRAM29, beginning with the first sector of the first ECC block of the twoECC blocks. This is because an ECC block is not completed and an errorcannot be corrected unless there are two consecutive ECC blocks. Thefirst sector of the two ECC blocks is determined by checking if thelow-order five bits contain “00000B”.

[0074] Each time at least one row (182 bytes) of data is accumulated inthe SRAM 29, an ECC-PI corrector 30 reads the data from the SRAM 29 inthe row direction, corrects an error with PI parity data if any, andwrites corrected data into the SRAM 29. After PI correction is made forall rows in the two consecutive ECC blocks and corrected data is writtenin the SRAM 29, an ECC-PO corrector 31 starts PO correction.

[0075] The ECC-PO corrector 31 reads 208 bytes of data of an ECC blockfrom the SRAM 29 in the column direction of the memory map to perform POcorrection with PO parity data. After PO correction is made for allcolumns (that is, 182 bytes), an ID detector 32 and a de-scrambler 33sequentially access 2064 bytes, composed of the ID, IED, CP, main data,and EDC parity data, and reads them from the SRAM 29.

[0076] The ID detector 32 detects the ID again from the data read fromthe SRAM 29 and sends the sector address to the de-scrambler 33. Thede-scrambler 33 uses the sector address, received from the ID detector32, to de-scramble 2048 bytes of main data included in the data readfrom the SRAM 29. Data de-scrambled by the de-scrambler 33 is sent to anEDC error detector 34, which uses the EDC to check to see if there is anerror.

[0077] In response to a detection result from the EDC error detector 34indicating that there is no error, a DRAM 35 writes therein the datade-scrambled by the de-scrambler 33. On the other hand, in response to adetection result from the EDC error detector 34 indicating that there isan error, the DRAM 35 does not write the data de-scrambled by thede-scrambler 33. Then, the EDC error detector 34 sends an instruction tothe servo controller 36 to read the same data again from the opticaldisk 23. The servo controller 36 moves the pickup 22 to access a desiredsector address again. This operation is called generally as a retry.

[0078] Actually, when the EDC error detector 34 detects an error withthe use of the EDC, one sector of de-scrambled data is already writtenin the DRAM 35. Therefore, if an error is detected, the address pointerof the DRAM 35 must be backspaced one sector. The data written in theDRAM 35 is read sequentially by an MPEG decoder 37 and is de-compressedaccording to the MPEG standard for generating the video signal and theaudio signal. Note that de-interleaving may also be performed afterreading data from the SRAM 29.

[0079] In the above description, an ECC block is composed of a pluralityof data sectors. As will be described, each data sector may also bedivided for distribution between two ECC blocks. As shown in (A) in FIG.9, one 6×344 data sector may be divided into two in the columndirection. That is, as shown in (A) in FIG. 9, the 12×172 data sectorshown in FIG. 7 is divided into two: a 6×172 first divided data sector(ith data sector is i_(—)1) composed only of odd-numbered rows and a6×172 second divided data sector (ith data sector is i_(—)2) composedonly of even-numbered rows.

[0080] Those data sectors are distributed in such a way that a divideddata sector on the left-hand side belongs to ECC block 1 and a divideddata sector on the right-hand side belongs to ECC block 2. Whenrepresenting the allocation as in the example described above, the datasectors are allocated as shown in (A) in FIG. 10. In this allocation,the data sector allocation is different from that shown in (B) in FIG. 6but the memory address allocation is the same. In this case, the datasector allocation is as shown in (B) in FIG. 11. The memory map beforeinterleaving is shown in (A) in FIG. 11.

[0081] In the example in (B) in FIG. 11, each time 12 rows (=2×6 rows)are output from each two divided data sectors, the PO parity rows, onefor each of ECC blocks 1 and 2, are output. This output method orderlyplaces main data on the recording medium, making memory access atreproduction time easy.

[0082] More generally, a data sector, given as M×N, is divided into twoin the column direction to generate a first divided data sector and asecond divided data sector, each composed of M rows and N/2 columns.They are distributed between two ECC blocks. And, when data isinterleaved, the PO rows, one for each ECC block, are inserted each time(M×2) rows are output from the first divided data sector and the seconddivided data sector (each two data sectors). In other words, a datasector, given as R(=M×2)×C(=N/2), is divided into two to generate an(R/2)×C first divided data sector composed of odd-numbered rows and an(R/2)×C second divided data sector composed of even-numbered rows. Theyare distributed between two ECC blocks. When data is interleaved, the POrows, one for each ECC block, are inserted each time R rows are outputfrom the first divided data sector and the second divided data sector(each two data sectors).

[0083] Next, a frame sync code recording and reproducing method in thisembodiment will be described more in detail. The NRZ conversion and syncdetector 25 counts the number of bits beginning at the position where aframe sync code is detected to predict the next frame sync codeposition. If the next frame sync code does not appear within severalbits before and after the predicted position, the NRZ conversion andsync detector 25 inserts a pseudo frame sync code at the predictedposition to prevent a condition in which the frame sync code cannot beread due to a defect.

[0084] For example, assume that two consecutive frame sync codes can bedetected. In this case, an attempt is made to establish sectorsynchronization assuming that frame synchronization has beenestablished. On a conventional DVD, the first frame sync code in eachsector is a unique code that is different from that of other frame synccodes. This frame sync code is called SY0. This SY0 appears at a fixedinterval of 26 sync frames. The NRZ conversion and sync detector 25 usesSY0, which is detected normally at reproduction time, to predict thenext SY0. This is done simply by counting 26 frame sync codes to checkto see if the next SY0 appears. Because SY0 appears every 26 sync framesas described above, the next SY0 may be predicted simply by countingsync frames.

[0085] However, in the embodiment described above, the rows of twoconsecutive ECC blocks are recorded alternately on the optical disk 23according to the memory map of the DRAM 19 such as the one shown in (B)in FIG. 6. Therefore, if the unique sync code is used only in the firstframe of a sector as on a DVD, SY0 is not generated at a fixed frequencyin the physical sectors of the signals recorded on the optical disk 23as shown in FIG. 8. It should be noted that the sync code itself is notstored in the DRAM 19 but is added by the modulation and frame syncadding unit 20 at a 91-byte interval and then recorded on the opticaldisk 23.

[0086] That is, when protection is provided beginning with the start oftwo ECC blocks as shown in FIG. 8, the sync frame SY0 appears at thestart of data sector 1 indicated by 41, then, after two sync frames, thesync frame SY0 appears at the start of data sector 2 indicated by 42,then, after 50 sync frames, the sync frame SY0 appears at the start ofdata sector 3 indicated by 43, and then, after two sync frames, the syncframe SY0 appears at the start of data sector 4 indicated by 44.Thereafter, the interval between two sync frames (SY0) alternatesbetween two and 50.

[0087] In this case, it must be decided which of two ECC blocks thedetected SY0 belongs to. To do so, it is necessary, after detecting theSY0 normally, to use two counters at the same time where two values arestored, one for SY0 that is two sync frames ahead and the other for SY0that is 50 sync frames ahead, in order to judge which will come next.However, this method makes the circuit complicated.

[0088] Thus, in this embodiment, 2060 bytes of data composed of maindata, ID, IED, and CP are written in the SRAM 12 such that theallocation is as shown in the memory map in (A) in FIG. 9. Then, the EDCencoder 14 reads data to generate a four-byte EDC and writes it in theSRAM 12. It should be noted that, as shown in (A) in FIG. 9, a datasector, 6×344, is divided into two in the column direction and that anarea is reserved in the SARM for ECC-PI parity data which will begenerated later.

[0089] That is, a 12×172 data sector shown in FIG. 7 is divided into twoas shown in (A) in FIG. 9: a 6×172 first divided data sector (i_1 forith data sector) composed only of odd-numbered rows and a 6×172 seconddivided data sector (i_2 for ith data sector) composed only ofeven-numbered rows. The divided data sectors on the left hand side formECC block 1, while the divided data sectors on the right hand side formECC block 2.

[0090] After 192 rows for 32 sectors (192 rows, 16 sectors×2) aregenerated as shown in (A) in FIG. 9, the scrambler 15 scrambles maindata as in the example described above and writes scrambled data in theSRAM 12. Next, the ECC-PO encoder 16 reads 192 rows (bytes) of data fromthe SRAM 12 in the column direction, generates 16 bytes of PO paritydata, and writes it in the PO parity area in the SRAM 12. This isrepeated for 344 columns (=172 columns×2). Then, the ECC-PI encoder 17reads 172 columns (bytes) of data from the SRAM 12 in the row directionas shown in (A) in FIG. 9, generates 10 bytes of PI parity data, andwrites it in the parity area of the SRAM 12. This is repeated for 416rows (208 rows×2).

[0091] The above operation generates two ECC blocks, that is, first ECCblock 1 on the left-hand side and second ECC block on the right-handside, as shown in (A) in FIG. 9. As in the above example, the sectoraddress is incremented by one for each of consecutive data sectors.

[0092] Next, the interleave processor 18 reads data from the SRAM 12 andwrites it into the DRAM 19 while interleaving as shown in (B) FIG. 9.Data is interleaved by adding the rows of the ECC blocks alternately asdescribed above; that is, the first row of the first ECC block is read,then the first row of the second ECC block is read, then the second rowof the first ECC block is read, then the second row of the second ECCblock is read, and so on. The PO rows of the two ECC blocks areinserted, one PO row (182 bytes) of one of two ECC blocks every 12 rows(six rows×2).

[0093] The above operation accumulates data as shown in the memory mapof the DRAM 19 in (B) in FIG. 9. Apparently, the memory map in (A) inFIG. 9 looks almost the same as that in (B), and data in the SRAM 12 anddata in the DRAM 19 do not seem to be interleaved. However, interleavingin this context refers to the relation between data in ECC blocks anddata written on the optical disk 23. Because data is written on the diskacross ECC blocks, it can be said that data is interleaved.

[0094]FIG. 10 shows a memory map created from the memory map in FIG. 9to make interleaving easy to understand. Both memory maps areequivalent. Section (A) in FIG. 10 is the memory map of the SRAM 12. Inthe memory map, the first ECC block is composed of 208 rows×182 columnsincluding 32 6×172 first divided data sectors, 16×172 PO parity data,and 208×10 PI parity data. Similarly, the second ECC block is composedof 208 rows×182 columns including 32 second divided data sectors. Thecontents are the same as those in (A) in FIG. 9. The data in this SRAMis interleaved into the memory map of the DRAM 19 as shown in (B) inFIG. 10. The memory map in (B) in FIG. 10 is the same that in (B) inFIG. 9.

[0095] The interleaved data read sequentially from the DRAM 19 ismodulated in the manner described above, has a frame synch code attachedevery 91 bytes, and is NRZI-converted for recording on the optical disk23.

[0096]FIG. 12 shows how physical sectors, including data and frame synccodes, are recorded on the optical disk 23. The sync frame SY0,indicated by 51, 52, and 53, at the start of a sector is allocated at aregular interval of 26 sync frames. In FIG. 12, Fn is a relative framenumber. Also, data sector 1_1 a corresponds to the first-half 91 columns(bytes) of data sector 1_1 in each (B) in FIG. 9 and FIG. 10, and datasector 1_b corresponds to the last-half 81 columns (bytes) of datasector 1_1 and 10 bytes of PI parity data. Other data sectors areallocated in the same way. Because the sync frame SY0 may be recordedand reproduced at a regular interval in this way, sector synchronizationmay be established at reproduction time with a simple circuit.

[0097] The reproduction operation in this case is similar to that of theconfiguration in FIG. 8 described above. The following describes theoperation simply. Each time at least one row (182 bytes) of data isaccumulated in the SRAM 29, the ECC-PI corrector 30 in FIG. 5 reads datafrom the SRAM 29 in the row direction, corrects an error with PI paritydata if any, and writes corrected data into the SRAM 29. After PIcorrection is made for all rows in the two consecutive ECC blocks andcorrected data is written in the SRAM 29, the ECC-PO corrector 31 startsPO correction.

[0098] The ECC-PO corrector reads 208 bytes of data from the SRAM 29 inthe column direction of the memory map to perform PO correction with POparity data for all columns of two ECC blocks, that is, 364 columns(=182 columns×2). After that, sector data extending across two ECCblocks (that is, 2064 bytes composed of the ID, IED, CP, main data, andEDC parity data) is sequentially accessed and then data is read from theSRAM 29.

[0099] In the above description, a 12×172 data sector is used as anexample. With a data sector given as an M×N data sector, the data sectormay be divided into two in the column direction to generate a firstdivided data sector and a second divided data sector, each composed of Mrows and N/2 columns. When data is interleaved, one PO row of one of twoECC blocks is inserted each time M rows (each data sector) are outputfrom the first divided data sector and the second divided data sector.In other words, a data sector, given as an R(=M×2)×C(=N/2) data sector,is divided into two to generate an (R/2)×C first divided data sectorcomposed of odd-numbered rows and an (R/2)×C second divided data sectorcomposed of even-numbered rows. When data is interleaved, one PO row ofone of two ECC blocks is inserted each time (R/2) rows (each datasector) are output from the first divided data sector and the seconddivided data sector.

[0100] <Second Embodiment>

[0101] Next, a second embodiment of the present invention will bedescribed. FIG. 13 shows data allocation on a recording medium in thesecond embodiment of the present invention. In this embodiment, aninterleave method is used in which data, which is error-correction-codedby the product coding method, is distributed on a recording medium. Asshown in FIG. 13, with two consecutive product-coded ECC blocks, EB1 andEB2, as a set, the first byte in the first row of the first ECC blockEB1 is followed by the second byte in the first row of the second ECCblock EB2, which is followed by the third byte in the first row of thefirst ECC block EB1, which is followed by the fourth byte in the firstrow of the second ECC block EB2. In this way, an odd-numbered byte inthe first row of the first ECC block is followed by an even-numberedbyte in the first row of the second ECC block EB2. This sequence isrepeated until the end of the first row. In FIG. 13, this datacombination is represented as EB1_1(EB2_1).

[0102] Because an ECC block is composed of 208 rows (bytes) eachcomposed of 182 columns (bytes) as described above, the 181st byte inthe first row of the first ECC block EB1 is followed by the 182nd bytein the first row of the second ECC block EB2. Then, the first byte inthe first row of EB2 is followed by the second byte in the first row ofEB1. In the same way, an odd-numbered byte of EB2 is followed by aneven-numbered byte of EB1, and this is repeated on a byte basis untilthe end of the first row. In FIG. 13, this data combination isrepresented as EB2_1(EB1_1).

[0103] Next, the same data allocation is performed for the second rowsof EB1 and EB2. That is, kth byte of one of the ECC blocks is followedby the (k+1)th byte of the other ECC block on a byte basis until the endof the second row. Data is allocated in this sequence for all rows ofEB1 and EB2.

[0104] As in the first embodiment, the PO parity data of the two ECCblocks is read, one row for each sector of the ECC blocks. For example,after the last byte (that is, 182nd byte) in the last row of the firstsector of the first ECC block EB1 is read, the first byte in the firstPO parity row of the first ECC block EB1 is read and then the secondbyte in the first PO parity row of the second ECC block EB2 is read. Byreading data as described above, data is written in the memory of therecording system (DRAM 19 in FIG. 5) of the data recording andreproducing apparatus in the same order in which data is stored in thearray on the optical disk shown in FIG. 13.

[0105] Although data is interleaved when read from the SRAM in thisembodiment, data may also be interleaved when written into the DRAM. Inaddition, data may be interleaved when written into the SRAM , and theEDCs and ECCs may be generated by reading the data while de-interleavingit.

[0106] When making PI corrections in the optical disk reproductionsystem in this embodiment, PI error correction processing is performedtwice each time two rows from the two ECC blocks (182 bytes×2), one fromeach, are written in the memory (corresponds to SRAM 29 in FIG. 5). POcorrections are made after PI corrections are made for all rows of thetwo ECC blocks as in the first embodiment.

[0107] Assume that a relatively short burst error has occurred in threepositions when an optical disk is reproduced in the second embodiment.The errors are an eight-byte error at a position indicated by 61, afive-byte error at a position indicated by 62, and a 10-byte error at aposition indicated by 63, respectively, in FIG. 13.

[0108]FIG. 14 shows the error distribution of de-interleaved data atreproduction time. If data bytes were not replaced on a byte basis atrecording time, the errors would remain in the rows. On the other hand,in this embodiment, burst errors are distributed between two ECC blocks.The first ECC block EB1 includes four bytes of error, two bytes oferror, and five bytes of error, while the second ECC block includes fourbytes of error, three bytes of error, and five bytes of error,respectively. If the number of bytes of an error is odd as in thefive-byte burst error in the 20th row, the number of error in one ECCblock is one byte longer than that of the corresponding error in theother ECC block. Dn in FIGS. 13 and 14 indicates a relative data numberin each row.

[0109] As described above, the PI parity data on a DVD is 10 bytes long,meaning that five symbols (bytes) may usually be corrected. Therefore,in the conventional method in which data bytes are not replaced on abyte basis at recording time, the five-byte error in the above examplecan be corrected but the remaining eight-byte error and the 10-byteerror cannot. On the other hand, because the number of bytes of arelatively short burst error included in a row in each ECC block may bereduced to about ½ in this embodiment, the eight-byte error and 10-byteerror in the above example are distributed between two ECC blocks asfour bytes of error and five bytes of error. Therefore, all errors maybe corrected

[0110] In this embodiment, the length of a relatively short burst errorincluded in each ECC block may be reduced to about ½. As describedabove, if there is no random error, the maximum length of a correctableburst error in the conventional DVD format is about 10 μm. Therefore,when the linear density is doubled, the maximum length of a defectcorrectable with PI parity data is about 5 μm. On the other hand,because a burst error about two times in length may be corrected in thisembodiment, the maximum length of a defect correctable with PI data isabout 10 μm even if the linear density is doubled. For the lineardensity of a DVD, a burst error in about up to 20 μm may be correctedwith PI data.

[0111] If a relatively short burst error occurs in the same row of thetwo ECC blocks, the number of error bytes in the rows is averaged inthis embodiment. Therefore, the probability with which an uncorrectableerror occurs is lowered.

[0112] In this embodiment, the PO parity rows of the two ECC blocks areread, one row for each sector of the ECC blocks. Instead, with a 6×344data sector divided into two (that is, the first divided data sector andthe second divided data sector) for distribution data to two ECC blocksas shown in (A) in FIG. 9, data may be interleaved in such a way thatthe PO rows of both ECC blocks (=182 bytes×2) are inserted every twodata sectors, that is, every 24 rows (12 rows of the first divided datasector and 12 rows of the second divided data sector), and theninterleaving in the second embodiment is performed. This allows maindata to be orderly sequenced on a recording medium in the secondembodiment, making memory access at reproduction time easy.

[0113] In addition, with a 6×344 data sector divided into two (that is,the first divided data sector and the second divided data sector) fordistribution data to two ECC blocks as shown in (A) in FIG. 9, data maybe interleaved in such a way that one PO row of one of two ECC blocks isinserted for each data sector, that is, every 12 rows (six rows of thefirst divided data sector and six rows of the second divided datasector) and then interleaving in the second embodiment is performed.This allows the unique sync frame SY0 to be recorded at the start of aphysical sector at a fixed frequency.

[0114] The present invention is not limited to the above embodiments.For example, although two types of product code, PI parity and POparity, are used in the embodiments, the present invention is alsoapplicable when three or more types of product code are used.

[0115] Although the two corresponding rows in two product code blocks(EB1 and EB2) are alternately switched every byte in the secondembodiment, the rows may also be switched alternately every 2 bytes, 13bytes, 14 bytes, or 91 bytes that are prime numbers of 182 bytes thatform one row. The fewer the number of bytes, the more enhanced theability to correct relatively short burst errors. In addition, theinterleaved digital signal in each embodiment may be transmitted in thewired or wireless mode or distributed over the Internet.

[0116] As described above, the method according to the present inventionreproduces data from a recording medium on which the kth rows of atleast two ECC blocks are sequentially recorded, which are followedsequentially by the (k+1)th rows, for all rows of the ECC blocksrepeatedly. Therefore, if a serious burst error spanning two ECC blocksoccurs, data reproduced from the recording medium that contains theerror is distributed between two or more ECC blocks and therefore thesize of the error included in one ECC block is reduced to ½ or smalleras compared to that of the conventional method. Also, because the paritydata is recorded in a unique allocation method without increasing thenumber of parity words, the maximum burst-error correctable length maybe increased in a simple configuration without increasing redundancy.This is very efficient for increasing the data linear density.

[0117] In addition, with the consecutive two ECC blocks as a set, datais recorded on a recording medium in such a way that the odd-numbereddata unit in the first row of one of the ECC blocks and theeven-numbered data unit in the first row of the other ECC block arealternately switched on a data unit basis. Then, the even-numbered dataunit in the first row of one of the ECC blocks and the odd-numbered dataunit in the first row of the other ECC block are alternately switched ona data unit basis. This is repeated for all rows in the two ECC blocks.Therefore, if a relatively small error occurs, the burst error lengthmay be averaged in the corresponding rows and the probability with whichan uncorrectable error occurs becomes lower than that of theconventional apparatus. Thus, the apparatus according to the presentinvention is very efficient for increasing the data linear density.

[0118] It should be understood that many modifications and adaptationsof the invention will become apparent to those skilled in the art and itis intended to encompass such obvious modifications and changes in thescope of the claims appended hereto.

What is claimed is:
 1. A digital signal processing method for recordingand reproducing digital signals of data to and from a recording mediumon an ECC (Error Correction Code) block basis, said ECC block beinggenerated by product-coding a predetermined number of words of digitalsignals and parity data, wherein, with n (n≧2) consecutive ECC blocks asa set, kth rows of the ECC blocks are recorded sequentially and then(k+1)th rows are recorded sequentially for all rows of the ECC blocks insuch a way that first rows of the ECC blocks of the set are recordedsequentially and then second rows are recorded sequentially on therecording medium.
 2. A digital signal processing method for recordingand reproducing digital signals of data to and from a recording mediumon an ECC block basis, said ECC block being generated by product-codinga predetermined number of words of digital signals and parity data,wherein, with two consecutive ECC blocks as a set, a sequence ofoperations is repeated for all rows of the two ECC blocks of the set,said sequence of operations being executed in such a way that anodd-numbered data unit in a first row of one of the ECC blocks of theset and an even-numbered data unit in a first row of the other ECC blockare alternately switched on a data unit basis and recorded on therecording medium and then an even-numbered data unit in the first row ofone of the ECC block and an odd-numbered data unit in the first row ofthe other ECC block are alternately switched on a data unit basis andrecorded on the recording medium.
 3. A data recording and reproducingapparatus that records and reproduces digital signals of data to andfrom a recording medium on an ECC block basis, said ECC block beinggenerated by product-coding a predetermined number of words of digitalsignals and parity data, said apparatus comprising: ECC block generatingmeans for generating ECC blocks by a product-coding method, each ECCblock including a predetermined number of words of main data, auxiliaryinformation including a sector address, and parity data; interleavingmeans for sequentially outputting, with n (n≧2)consecutive ECC blocks asa set, kth rows and then (k+1)th rows of the ECC blocks of the set insuch a way that first rows of the ECC blocks of the set are outputsequentially and then second rows are output sequentially, saidconsecutive ECC blocks being included in the ECC blocks generated bysaid ECC block generating means; recording means for recording signals,output by said interleaving means, on said recording means with framesync codes attached; reproducing means for reproducing the signals fromsaid recording medium; de-interleaving means for de-interleaving thesignals reproduced by said reproducing means based on the sectoraddresses and for outputting said ECC blocks arranged in an originalorder; and decoding means for de-modulating the main data using data inthe ECC blocks obtained by said de-interleaving means.
 4. The datarecording and reproducing apparatus according to claim 3, wherein saidECC block generating means sequentially generates a plurality of ECCblocks each composed of a predetermined number of words and eachcomprising a plurality of divided data sectors each being one of twoM×(N/2) data sectors generated by dividing an M×N data sector composedof the main data and the auxiliary information, into two in a columndirection; a predetermined number of bytes of first parity datagenerated from row-direction elements of the plurality of divided datasectors; and a predetermined number of bytes of second parity datagenerated from column-direction elements of the divided data sectors,the first parity data or the second parity data being generated from therow-direction elements of the second parity data or the column-directionelements of the first parity data, wherein, with two consecutive ECCblocks, generated by said ECC block generating means, as a set, saidinterleaving means sequentially outputs kth rows, and then sequentiallyoutputs (k+1) throws, of two divided data sectors corresponding to eachof the ECC blocks in such a way that each of first rows of the twodivided data sectors, each belonging to one of the ECC blocks of theset, and corresponding first parity data are output sequentially andthen each of second rows is output sequentially and, each time M rows ofthe two divided data sectors are output, the second parity data isoutput alternately for one and the other of the two ECC blocksalternately, and wherein said recording means records the signals,output by said interleaving means, with the frame sync codes attached ata regular interval.
 5. The data recording and reproducing apparatusaccording to claim 3, wherein said ECC block generating meanssequentially generates a plurality of ECC blocks each composed of apredetermined number of words and each comprising a plurality of divideddata sectors each being one of two M×(N/2) data sectors generated bydividing an M×N data sector composed of the main data and the auxiliaryinformation, into two in a column direction; a predetermined number ofbytes of first parity data generated from row-direction elements of theplurality of divided data sectors; and a predetermined number of bytesof second parity data generated from column-direction elements of thedivided data sectors, the first parity data or the second parity databeing generated from row-direction elements of the second parity data orcolumn-direction elements of the first parity data, wherein, with twoconsecutive ECC blocks, generated by said ECC block generating means, asa set, said interleaving means sequentially outputs kth rows, and thensequentially outputs (k+1)th rows, of two divided data sectorscorresponding to each of the ECC blocks in such a way that each of firstrows of the two divided data sectors, each belonging to one of the ECCblocks of the set, and corresponding first parity data are outputsequentially and then each of second rows is output sequentially and,each time (2×M) rows of the two divided data sectors are output, thesecond parity data is output for the two ECC blocks.
 6. A data recordingand reproducing apparatus that records and reproduces digital signals ofdata to and from a recording medium on an ECC block basis, said ECCblock being generated by product-coding a predetermined number of wordsof digital signals and parity data, said apparatus comprising: ECC blockgenerating means for generating ECC blocks by a product-coding method,each ECC block including a predetermined number of words of main data,auxiliary information including a sector address, and parity data;interleaving means for repeating, with two consecutive ECC blocks as aset, a sequence of operations for all rows of the two ECC blocks of theset, said sequence of operations being executed in such a way that anodd-numbered data unit in a first row of one of the ECC blocks of theset and an even-numbered data unit in a first row of the other ECC blockare alternately switched on a data unit basis and then an even-numbereddata unit in the first row of one of the ECC block and an odd-numbereddata unit in the first row of the other ECC block are alternatelyswitched on a data unit basis; recording means for recording signals,output by said interleaving means, on said recording means with framesync codes attached; reproducing means for reproducing the signals fromsaid recording medium; de-interleaving means for de-interleaving thesignals reproduced by said reproducing means based on the sectoraddresses and for outputting said ECC blocks arranged in an originalorder; and decoding means for de-modulating the main data using data inthe ECC blocks obtained by said de-interleaving means.
 7. A datarecording medium on which digital signals of data are recorded on an ECCblock basis, said ECC block being generated by product-coding apredetermined number of words of digital signals and parity data, p1wherein, with n (n≧2)consecutive ECC blocks as a set, kth rows of theECC blocks are recorded sequentially and then (k+1)th rows are recordedsequentially for all rows of the ECC blocks in such a way that firstrows of the ECC blocks of the set are recorded sequentially and thensecond rows are recorded sequentially.
 8. A recording medium on whichdigital signal of data are recorded on an ECC block basis, said ECCblock being generated by product-coding a predetermined number of wordsof digital signals and parity data, wherein, with two consecutive ECCblocks as a set, a sequence of operations is repeated for all rows ofthe two ECC blocks of the set, said sequence of operations beingexecuted in such a way that an odd-numbered data unit in a first row ofone of the ECC blocks of the set and an even-numbered data unit in afirst row of the other ECC block are alternately switched on a data unitbasis and then an even-numbered data unit in the first row of one of theECC block and an odd-numbered data unit in the first row of the otherECC block are alternately switched on a data unit basis.